scholarly journals Control Strategy Based on Arm-Level Control for Output and Circulating Current of MMC in Stationary Reference Frame

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4160
Author(s):  
Waqar Uddin ◽  
Tiago D. C. Busarello ◽  
Kamran Zeb ◽  
Muhammad Adil Khan ◽  
Anil Kumar Yedluri ◽  
...  
Keyword(s):  
Reference Frame ◽  
Control Method ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Effective Control ◽  
Level Control ◽  
Circulating Current ◽  
Stationary Reference Frame ◽  
Pr Controller ◽  
Dc Component

This paper proposed a control method for output and circulating currents of modular multilevel converter (MMC). The output and circulating current are controlled with the help of arm currents, which contain DC, fundamental frequency, and double frequency components. The arm current is transformed into a stationary reference frame (SRF) to isolate the DC and AC components. The AC component is controlled with a conventional proportional resonant (PR) controller, while the DC component is controlled by a proportional controller. The effective control of the upper arm and lower arm ultimately controls the output current so that it delivers the required power to the grid and circulating current in such a way that the second harmonic component is completely vanished leaving behind only the DC component. Comparative results of leg-level control based on PR controller are included in the paper to show the effectiveness of the proposed control scheme. A three-phase, five-level MMC is developed in MATLAB/Simulink to verify the effectiveness of the proposed control method.

scholarly journals Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1264 ◽  
Author(s):  
Fatemeh Shahnazian ◽  
Ebrahim Adabi ◽  
Jafar Adabi ◽  
Edris Pouresmaeil ◽  
Kumars Rouzbehi ◽  
...  
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
Second Harmonic ◽  
Power Grid ◽  
Harmonic Component ◽  
Current Control ◽  
Energy Sources ◽  
Stable Operation ◽  
Multilevel Converters ◽  
Steady State Operation

This paper presents a dynamic model of modular multilevel converters (MMCs), which are considered as an effective interface between energy sources and the power grid. By improving the converter performance, appropriate reactive power compensation is guaranteed. Modulation indices are calculated based on detailed harmonic evaluations of both dynamic and steady-state operation modes, which is considered as the main contribution of this paper in comparison with other methods. As another novelty of this paper, circulating current control is accomplished by embedding an additional second harmonic component in the modulation process. The proposed control method leads to an effective reduction in capacitor voltage fluctuation and losses. Finally, converter’s maximum stable operation range is modified, which provides efficiency enhancements and also stability assurance. The proficiency and functionality of the proposed controller are demonstrated through detailed theoretical analysis and simulations with MATLAB/Simulink.

scholarly journals The.main types of wind turbines-generators in the power supply system

2022 ◽  
Vol 23 (5) ◽  
pp. 71-85
Author(s):  
V. A. Novobritsky ◽  
D. S. Fedosov
Keyword(s):  
Second Harmonic ◽  
Short Circuit ◽  
Separation Of Variables ◽  
Harmonic Component ◽  
Relay Protection ◽  
Short Circuit Current ◽  
Current Transformer ◽  
Correct Operation ◽  
Protection Devices ◽  
Dc Component

THE PURPOSE. This paper considers the problem of relay protection functioning when the current transformer reaches the saturation mode which is provided by transient processes.METHODS. MATLAB Simulink software environment allows reproducing the method of statespace representation by using structural blocks. The model is verified by comparison the time to saturation, obtained by calculation and according to the graphical data of the model. The separation of variables method extracts and graphically displays the investigated components.RESULTS. This paper reveals that applying the requirements of IEC 61869-2:2012 standard, which determines the worst combination of series of unfavorable factors for current transformers in transient mode, can influence a serious impact on the correct operation of relay protection based on current, reactance or differential principle of action. Saturation of the current transformer can lead to both negative results: false operation of relay protection devices and their failure.CONCLUSION. According to the results of the study, it was determined that the presence of a DC component in the primary short-circuit current has the greatest effect on the protection operation. The delays in the restoration of the RMS value of the short-circuit current reached up to 0.3 seconds, which is comparable with the response time of the second protection zones for microprocessor-based relay protection devices. The DC component of the primary current and the presence of residual magnetic induction of the current transformer provides the largest content of the magnetization current, the largest angular error and also the largest content of the second harmonic component in the secondary short-circuit current.

scholarly journals A control method for parallel inverters in Microgrid based on sliding mode and droop controls

2016 ◽  
Vol 19 (1) ◽  
pp. 40-50
Author(s):  
Hoa Thi Xuan Pham ◽  
Huy Minh Nguyen
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Sliding Mode ◽  
Tracking Error ◽  
Harmonic Component ◽  
Voltage Control ◽  
Nonlinear Loads ◽  
Proportional Integral ◽  
Pr Controller ◽  
Islanded Microgrid

Robust control and flexible operation are the major objectives of islanded microgrid. A microgrid can have different configurations with linear loads and nonlinear loads. The harmonic current caused by nonlinear loads make Proportional Integral (PI) or Proportional Integral Derivative (PID) voltage controller far beyond excellent performance in case of microgrid operating in islanded mode. Additionally, the robustness of the PID closed loop system can not be guaranteed. The voltage control by using Proportional resonant (PR) controller are recommended. Although PR controller has the ability to sinusoidal signals. However, PR controller has a slight deviation of the frequency of selected harmonic component. This paper presents a Sliding Mode Control (SMC) for voltage control of parallel inverters operating in islanded microgrid. This controller can enhance the robustness of control system and reduced-state tracking error. The stability of the closed-system is verified by means of Lyapunov stability criterion. The control structure is based on the inner sliding mode closed-loop and the outer droop control loop. The main aim of this paper is to design inner controllers to enhance the dynamics of the microgrid. The results obtained from the simulation of Matlab.

The Fuzzy Self-Tuning PID Control for Boiler Drum Water Level

2012 ◽  
Vol 198-199 ◽  
pp. 1231-1234 ◽  
Author(s):  
Yong Sheng Zhang ◽  
Shu Qin Zhao
Keyword(s):  
Fuzzy Logic ◽  
Water Level ◽  
Pid Control ◽  
Control Method ◽  
Effective Control ◽  
Level Control ◽  
Quality Of Water ◽  
Self Tuning ◽  
Boiler Drum ◽  
Time Lagged

In order to improve the control quality of water level for boiler drum, a fuzzy self-tuning PID level controller for boiler drum was designed based on the fuzzy logic principle. The fuzzy logic toolbox and Simulink module of Matlab software were used for the modeling of the water level control system of boiler drum. Numerical simulation was implemented. The result shows that the fuzzy self-tuning PID control has such virtues as smaller overshoot, shorter regulating time and stronger robustness than conventional three-element PID control. The fuzzy self-tuning PID control is especially effective for nonlinear system like boiler with multivariable, large time lagged and strong coupling. It is a very effective control method with widely application prospect.

scholarly journals Amplitude Control Method of Magnetic Flux Vertical Modulation Structure for TMR Magnetic Sensor Based on Harmonic Component of Modulated Signal

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 722
Author(s):  
Junsheng Zhang ◽  
Mengchun Pan ◽  
Qingfa Du ◽  
Jiafei Hu ◽  
Kun Sun ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Control Method ◽  
Amplitude Ratio ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Low Frequency ◽  
Magnetic Sensor ◽  
Modulation Method ◽  
Temperature Drift ◽  
Amplitude Control

Magnetic flux vertical modulation method based on piezoelectric resonance can reduce the 1/f noise of tunnel magnetoresistance (TMR) magnetic sensor and significantly improves the low-frequency magnetic field detectivity. However, the amplitude variation of the modulation structure will lead to the instability of the sensor output. In order to improve the amplitude stability of the modulation structure, an amplitude control method based on the amplitude ratio of the first and second harmonic components of the modulated signal was proposed. Compared with the piezoelectric or capacitive feedback method, this method does not require an independent amplitude conversion circuit, and has the advantages of simple structure, high control efficiency and strong anti-interference ability. The experimental results showed that the amplitude and temperature drift of the modulated structure was significantly suppressed, which is of great significance for enhancing the adaptability of the TMR magnetic sensor to the application environments.

scholarly journals Sensorless Speed Control of IPMSM Using Sliding Mode Observer Based on Active Flux Concept

2020 ◽  
Vol 93 (1-4) ◽  
pp. 1-9
Author(s):  
Fayza Boussekra ◽  
Abdessalam Makouf
Keyword(s):  
Reference Frame ◽  
Control Method ◽  
Sliding Mode ◽  
Design Method ◽  
Current Control ◽  
Sliding Mode Observer ◽  
Permanent Magnet Synchronous Motors ◽  
Interior Permanent Magnet ◽  
Stationary Reference Frame ◽  
Active Flux

This paper proposes a new speed and position sensorless control method of Interior permanent magnet synchronous motors (IPMSM) using sliding mode observer based on Active Flux concept. First, a new description of IPMSM dynamic model in the stationary reference frame using active flux concept is proposed. The model obtained suits for both SPMSM and IPMSM in the stationary reference frame, Therefore, all that sensorless controls proposed for SPMSM can be directly and easily applied to IPMSM. Secondly, from the measurement of the voltages and the currents, a new analysis of the observability property is developed. Then, the sliding mode observer (SMO) structure and its design method are described in the stationary reference frame by using the active flux equation. A “chattering” phenomenon is reduced by using this technique. The stability of the proposed SMO was verified using the Lyapunov function. The speed and position of the IPMSM are estimated based on back EMF which are related to the active flux. Moreover, the zero d-axis current control strategy is used to control the IPMSM. Finally, the proposed method on the proposed model has been simulated and tested to show the effectiveness of the proposed scheme.

Harmonic Homotopy Technique to Resonance Response of a Ship Rolls Model

2013 ◽  
Vol 838-841 ◽  
pp. 2231-2235
Author(s):  
Zhong Jin Guo ◽  
Dan Sun ◽  
Xiao Yan Ma
Keyword(s):  
Floquet Theory ◽  
Numerical Solutions ◽  
Second Harmonic ◽  
Harmonic Component ◽  
Homotopy Continuation ◽  
Wave Excitation ◽  
Resonance Response ◽  
Stable Solutions ◽  
Dc Component ◽  
Input Wave

The paper presents a harmonic homotopy technique to investigate the steady state resonance response of a ship rolls model. By means of polynomial homotopy continuation, all the possible solutions corresponding to the second-order superharmonic response are derived analytically, i.e. without numerical integration. The stabilities of the solutions are determined by the Floquet theory. The sharp resonance and influence of dc component of input wave excitation of ship rolls model are observed analytically and examined by numerical solutions. Furthermore, the gains of the bias, first and second harmonic terms of stable solutions are illustrated to show the importance of each harmonic component on resonance response.

Research on Fuzzy Control System of the Water Level for Steam Generator

2011 ◽  
Vol 383-390 ◽  
pp. 4184-4188
Author(s):  
Yong Sheng Zhang ◽  
Yun Yi Ma
Keyword(s):  
Fuzzy Logic ◽  
Control System ◽  
Fuzzy Control ◽  
Water Level ◽  
Steam Generator ◽  
Control Method ◽  
Effective Control ◽  
Level Control ◽  
Time Lagged

In order to improve the control quality of the water level for steam generator, a fuzzy level controller for steam generator is designed based on the fuzzy logic principle. The fuzzy logic toolbox and Simulink module of Matlab software are used for the modeling of the water level control system of steam generator. The operating condition of reducing load is calculated. Simulation result shows that the fuzzy control has such virtues as smaller overshoot, shorter regulating time and stronger robustness than the conventional three-element PID control. Fuzzy control is especially effective for nonlinear system like steam generator with multivariable, large time lagged and strong coupling. It is a very effective control method with widely application prospect.

scholarly journals Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

2021 ◽  
Author(s):  
Nasiru B. Kadandani ◽  
Mohamed Dahidah ◽  
Salaheddine Ethni ◽  
Musbahu Muhammad
Keyword(s):  
Control Method ◽  
Semiconductor Devices ◽  
Junction Temperature ◽  
Multilevel Converters ◽  
Control Approach ◽  
Circulating Current ◽  
Inherent Feature ◽  
Modular Multilevel Converters ◽  
Current Loading ◽  
Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

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